If it wasn’t for Jennifer Garner’s sweet performance of grief and disbelief, “Catch and Release” would be swimming in inertia. The jokes all fail to connect and the chemistry between the leads is nonexistent, but there’s an undercurrent of sadness to the film that’s interesting.

What Oscar-nominated screenwriter Susannah Grant has with her directorial debut, “Catch and Release,” is a sloppy ode to the realities of love. On top of that, she also wants to have her relationship fantasy cake and eat it too, so where’s the focal point of this creation? I’m still trying to figure that one out.

On the eve of her wedding, Gray (Jennifer Garner) learns of her fiancée’s sudden death. Destroyed by the news, she relies on her friends, Dennis (Sam Jaeger, “Lucky Number Slevin”) and Sam (Kevin Smith), to provide the comfort and shelter she needs. Trying to put her world back in order, she uncovers a life her fiancée kept hidden from her, including a one-night-stand (Juliette Lewis) and her son. Shattered, Gray finds solace in the arms of her fiancée’s loutish friend, Fritz (Timothy Olyphant, “Deadwood”).

Having written perhaps one of the best films on the exasperating state of sisterhood, “In Her Shoes,” it’s a crushing disappointment to watch Grant play it so safe with “Catch and Release.” Grant is torn between her instincts to plunge into the souls of her characters and excavate the most candid drama, and her fear that if she doesn’t defang her creation, it won’t play as the featherweight alternative for the beer-soaked Super Bowl celebration. The film ends up caught in the middle between characters that have a unique way of life about them and a story that feels bolted to the floor of convention no matter how much Grant struggles to free herself.

Gray’s emotional arc from wounded soul to liberated lady is the film’s only truly graceful plot thread, and the singular bit of business in the picture that’s fully realized. Played with exceptional befuddlement and puppy-dog slobber by Garner, Gray’s revelation that the love of her life wasn’t exactly the man she understood is afforded the attention to emotional detail that keeps “Catch” afloat during the worst of times. It’s a fascinating subplot to work with; that deep hole of confusion and anger when trust is not only broken, but shattered into a million jagged pieces. The subplot is the impetus of Grant’s storytelling, but this bronco bucks hard, and she can’t always keep a tight grip.

Once the tale drifts over to one of romance between Gray and Fritz, “Catch” unravels swiftly. If the extreme improbability of the hook-up doesn’t give you whiplash (Fritz rockets from a despicable drip to thoughtful Romeo in the blink of an eye), the absence of chemistry between Garner and the always toothless Olyphant will have you wishing a runaway city bus would smack both actors. Grant complicates things further by trying to shove in individual arcs for Dennis and Sam, while also paying off a paternity drama involving Lewis’s hippy-dippy character. Yikes. Now what was this film about again?

If you happen to be going to “Catch” to see Kevin Smith is his big acting debut (after a decade of bits and pieces), I wouldn’t purchase that ticket just yet. Smith’s merriment in his supporting role lifts the film up every time he’s onscreen, but shroud in bulky shirts emblazoned with “37,” and squeezing in a “Star Wars” reference, Smith is still playing to his hardcore fans. Coming from this critic who thinks Smith hung the moon, it’s a disappointment that “Catch” doesn’t push Smith harder, instead turning the former Silent Bob into, well, Talking Bob for a majority of the picture.

When Grant reaches for the syrup in the asinine finale, you’ll have to remind yourself that Garner is quite touching here, the first 30 minutes of the film capture the anxieties of loss rather well, and the “Colorado” fly-fishing vistas are breathtaking. “Catch and Release” is several parts of a terrific film, and if Grant wasn’t so lost inside her script, it might’ve packed much more of a wallop than the faint discharge of liberation it currently offers.